webpack.config.js

module.exports = {
  mode: process.env.NODE_ENV || "development",
  entry: {
    main: "./src/js/main.js"
  },
  output: {
    filename: "[name].js"
  },
  module: {
    rules: [
      {
        test: /\.(js|jsx)$/,
        loader: "babel-loader",
        options: {
          presets: ["@babel/preset-env", "@babel/preset-react"]
        }
      }
    ]
  },
  resolve: {
    extensions: [".js", ".jsx"]
  }
};